Fuel Cells — Hydrogen

A hydrogen fuel cell is an electrochemical cell that produces electricity from the reaction of hydrogen and oxygen. Fuel cells are an important part of the Energy Changes topic in AQA GCSE Combined Science Trilogy (8464). This lesson covers how hydrogen fuel cells work, their advantages and disadvantages, and how they compare with other energy sources.

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What Is a Fuel Cell?

A fuel cell is an electrochemical device that converts the chemical energy of a fuel directly into electrical energy. Unlike a battery, a fuel cell does not run down or need recharging — it produces electricity continuously as long as the fuel (hydrogen) and oxygen are supplied.

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How a Hydrogen Fuel Cell Works

In a hydrogen fuel cell:

1. Hydrogen gas ($\text{H}_2$H2​) is fed to the anode (negative electrode).
2. Oxygen gas ($\text{O}_2$O2​) from the air is fed to the cathode (positive electrode).
3. At the anode, hydrogen molecules are oxidised — they lose electrons.
4. The electrons flow through the external circuit, producing an electric current.
5. At the cathode, oxygen combines with the electrons and hydrogen ions to form water.

Overall Reaction

$2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}$2H2​+O2​→2H2​O